DOS

Hi

I am starting down the road of rebuilding my rear wheel because the current rim is worn out. The wheel is currently 28h 3x on drive side and 2x on nondrive. No idea why the builder built it that way. I have built wheel before but always the same pattern (3x) on both sides. I am inclined to rebuild the wheel the way it is just to learn a new trick but am curious, what is the advantage, if any, of the 3x/2x mix? Small weight savings from shorter spokes on one side?

tomtomtom123

I don't know but wouldn't the shorter spokes on non drive side by making it 2x cause it to need more tension? It might help to decrease the difference in tension between left and right sides.

Actually no. I just ran it through the calculator and the left tension dropped from 44 to 42%. A shorter spoke would cause the angle to become greater at the rim so the effect of the pull is also greater and needs less tension to compensate

Russ Roth

It is a slight weight savings that carries no real penalty. Typical rule of thumb is that you rebuild a hub the same way it was to prevent further damage to the spoke holes. They've deformed one way and the new angle would create further stretching and damage that can break the hole. Not certain how much difference 2x to 3x would make. Typically it's usually wanting to go from straight to 3x or 3x to straight.

WizardOfBoz

I had the same initial thought but then came to the same conclusion. The point above seems correct to me. The one thing I could think of was that the 3x would transmit torque better. This would lessen the torque transmitted through the smaller center portion of the hub. But the 3xDS /2xNDS setup seems to me to increase spoke tension on the DS (relative to use 2X) or to decrease the spoke tension on the NDS (relative to a 3X NDS). I'd think a simple 3X both sides would give you more even spoke tension. There is a slight weight savings as Russ Roth mentioned. Seems a lot fanciness for a few grams, and with negative spoke tension consequences.

I agree with Russ about relacing carefully to the original specs. Several decades ago, a drunk rear-ended me in a left turn lane on Costa Mesa Boulevard in California. I had just received my custom-made Paramount, and the force crumpled the rear triangle, and destroyed the rim. I can't complain, though, because though I rode the drunk's hood (like a really ugly, very surprised-looking 100kg hood ornament) my total injury was a slight nick on my knee. Anyhoo, the guy that relaced my wheel ignored Russ's guidance, and so my hub had visible spoke deformation (on a Campy Nuovo Record low flange!) for the rest of the bike's life. Still has 'em, though the bike is sitting in the garage. It's bugged me for nearly 40 years! Long story, whose moral is: Don't do this! Russ is right! Relace as original!

ThermionicScott 

In addition to tiny weight savings, 2x on the left will be a tiny bit stiffer than 3x. We're talking really small degrees though. Another vote for relacing it as original.

Andrew R Stewart 

Hub flanges get worn by spokes over the miles. When you remove the spokes one will see on the side of the flange,and between the spoke hole and the flange's OD, a wear/erosion spot. The spoke's elbow will indent the spoke hole a tad and over many cycles (pun intended) of flex and grit the flange will erode further along the line of contact with the spoke. This can, in the extreme,lead to flange cracking.

So when replacing spokes (in the OP's case a complete rebuilding) matching the spoke/flange contact reduces further erosion. Allowing the flange to become eroded in a second location (about the spoke hole) just gives the failure mode another path to explore. Andy

joeruge

I haven't run through any calculations, but I'm wondering if the 3X - 2X thing allowed the original wheel builder to use the same length spokes for both the drive and non-drive side. I sometimes build a wheel based at least partly on what spokes I have around and what I can work out with the hub and rim combo.

From what I've read, it is a good idea to re-lace a hub the same way it was originally laced. The original poster indicated he'd be replacing the rim. And he's using the same hub. But I didn't notice if he would be using the same spokes.

DOS

Thanks to everyone who pointed out the wisdom of relacing the same way as original to maximize hub durability. I hadn’t considered that issue.

As to the quote above, the spokes are different lengths. In fact the nds spokes are shorter than drive side, which would not be the case if the wheel was the same lacing pattern on both sides. I am working with a White T11 hub and Hed Belgium Plus rim. Drive side spokes are 291mm, nondrive are custom 285.5 according to paperwork from the wheel builder.Online calculators show that I should use 290.4mm ds and 284.9 on nds. So if I go with new, I’d use 291 and 285.

Regarding reusing spokes, I am on tne fence. These are pricey Sapim CX Ray spokes so reusing would save me $110, but new spokes would up my confidence in the rebuilt wheel’s durability. What are thoughts on the efficacy of reusing spokes?

joeruge

Hey, Thanks for giving those spoke lengths - very interesting. It would have been cool if they were the same length. Guess that was too much to hope for.

I am not a wheel building expert - obviously. But I am a cheap skate and saving $100 sounds good to me!
I would say, in my non-expert way, that if the original wheel lasted long enough to wear out the rim but not break spokes, that the original builder knew what they were doing and those spokes were not over-worked during the life of the wheel. I'd check with experts like Jobst Brandt on it, but I'd reuse them.They are probably fine. If however, you were experiencing spoke breakage, then no.

If you do reuse them, it would be up to you to build the wheel correctly - which means with enough tension in the spokes. The biggest cause for spoke failure, other than pot holes, is not using sufficient tension when the wheel it built. This causes fatigue failure, usually at the bend in the spoke (if they are bent!)

Just my cheap-skate thoughts.

Russ Roth

Why are you rebuilding/replacing? Just want a newer better rim and the wheel hasn't been around long or used enough to wear out the rim then reusing spokes will be ok for a decent amount of time. Spokes are a wear item though and should be replaced when the rim is worn or they start breaking. There are exceptions; especially in my experience with BMX race bikes where wheels can get toasted quick on a crash reusing expensive spokes was common or if you somehow screw up a wheel. But otherwise they have a finite life and you may find yourself rebuilding the wheel next year.

ThermionicScott 

That's an interesting idea, but at least with conventional hubs, the spoke lengths will be the closest for the same number of crosses on both sides.

Bill Kapaun

If the wheel is still intact-
Look at the nipples to see where the spoke end is in relation to the screw driver slot.
That will tell you if you want to favor longer/shorter or if the spoke is "just right".
Measure said spoke and add/subtract for the screw driver slot difference if any.

New spokes & nipples are a dream to work with compared to used.
At least get new nipples.
Thoroughly wire brush spoke threads.
Corrosion destroys a good sense of "feel" with the spoke wrench.

cpach

Reasons to do this include for shoots and giggles and to use existing spoke stock, and possibly for hubs with very unevenly sized hub flanges. I've done this simply based on available spoke stock before. It takes me a short amount of time more to lace up. There are some arguable advantages to half radial lacings, also it can look kinda cool (have this on one wheelset).

I would match the existing lacing pattern. Also if your spokes have been reliable and the need to relace really is just the rim, I'd personally reuse the spokes as they are if you're using a rim with the same ERD. It's nice because you can simply tape the two rims together and move the spokes over one at a time. Use new nipples though, they're cheap enough and it makes things easier.

Trakhak

Spokes in a correctly tensioned wheel can almost always be reused with no problems.

Reusing spokes---Jobst Brandt

DOS

Speaking of correctly tensioned wheels, the ones I have have been reliably true for 4 years without issues and were built by a pro wheelbuilder. So I assume that they were correctly tensioned originally. That said, I am a little concerned about getting tension right on my rebuild. I am using 28h HED Belgium plus rim and Sapim CX Ray spokes. Hed’s sight says max tension is 130kgf but doesn't give a recommended tension for Belgium Plus. Taking a quick measure of the spokes on the current wheel with worn out rim (tire mounted and inflated) the spoke tension comes out around 80kgf, which seems awfully low even recognizing that the measurement will be higher when I take tires off. So I am a bit perplexed about what tension to shoot for.

ThermionicScott 

On which side is the tension 80kgf? Hopefully you know that the tensions are different on each side of a rear wheel with a freewheel/cassette.

tomtomtom123

80 kgf may be ok for both sides of the front wheel, but I aim for 100. On my rear wheel the proportion is 44/100% and 130kgf right side means 57kgf left side, but because I have small 20" wheels that's more difficult to balance, I get between 49 to 65 left and 120 to 140 right, according to my tension meter, but it's inaccurate, so I only use it as a reference. I tension the right side as high as I comfortably feel is the maximum limit when it becomes difficult to turn with the popping sound of the grease no longer having an effect in making the nipple turn smoothly, then follow up on the left side. The rim is maybe offset 0.2mm to the left of the hub, better than having it to the right.
My tension reading is with the tire off.

berner

My rear wheel also is 3 cross on DS and 2 cross on NDS. The 3 cross spokes are on the tangent of the hub flange. This is the most effective angle for spokes that are already at quite high tension. It these spokes were a 2 cross, higher tension would be needed to do the same work.